PROPERTIES OF HYPOXANTHINEGUANINE-PHOSPHORIBOSYL-TRANSFERASE (HGPRTASE) IN A GOUT PATIENT WITH PARTIAL DEFICIENCY OF THIS ENZYME

Some physicochemical properties of HGPRTase were studied in hemolysates and fibroblasts of a gout patient with partial deficiency of this enzyme. In comparison to normal HGPRTase the mutant enzyme from erythrocytes was found to have an elevated apparent Km-value for hypoxanthine and guanine and a lower Km-value for PRPP. The patient's enzyme from erythrocytes is more stable at +4°C and +80°C, the enzyme from fibroblasts more labile than that of controls. The inhibition of the mutant enzyme by some purine nucleosides and-nucleotides differed from that found in controls. No evidence was shown for an inhibitor of the patient's HGPRTase from erythrocytes. Ultracentrifugation of hemolysate in a saccharose gradient revealed no difference in the sedimentation coefficient. © 1979 Springer-Verlag.